The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/unionfs/union_vnops.c

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    1 /*-
    2  * Copyright (c) 1992, 1993, 1994, 1995 Jan-Simon Pendry.
    3  * Copyright (c) 1992, 1993, 1994, 1995
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * Jan-Simon Pendry.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      @(#)union_vnops.c       8.32 (Berkeley) 6/23/95
   34  * $FreeBSD: releng/6.0/sys/fs/unionfs/union_vnops.c 145825 2005-05-03 11:05:33Z jeff $
   35  */
   36 
   37 #include <sys/param.h>
   38 #include <sys/systm.h>
   39 #include <sys/fcntl.h>
   40 #include <sys/stat.h>
   41 #include <sys/kernel.h>
   42 #include <sys/vnode.h>
   43 #include <sys/mount.h>
   44 #include <sys/namei.h>
   45 #include <sys/malloc.h>
   46 #include <sys/bio.h>
   47 #include <sys/buf.h>
   48 #include <sys/lock.h>
   49 #include <sys/sysctl.h>
   50 #include <sys/unistd.h>
   51 #include <sys/acl.h>
   52 #include <sys/event.h>
   53 #include <sys/extattr.h>
   54 #include <sys/mac.h>
   55 #include <fs/unionfs/union.h>
   56 
   57 #include <vm/vm.h>
   58 #include <vm/vnode_pager.h>
   59 
   60 #include <vm/vm_page.h>
   61 #include <vm/vm_object.h>
   62 
   63 int uniondebug = 0;
   64 
   65 #if UDEBUG_ENABLED
   66 SYSCTL_INT(_vfs, OID_AUTO, uniondebug, CTLFLAG_RW, &uniondebug, 0, "");
   67 #else
   68 SYSCTL_INT(_vfs, OID_AUTO, uniondebug, CTLFLAG_RD, &uniondebug, 0, "");
   69 #endif
   70 
   71 static vop_access_t     union_access;
   72 static vop_aclcheck_t   union_aclcheck;
   73 static vop_advlock_t    union_advlock;
   74 static vop_close_t      union_close;
   75 static vop_closeextattr_t       union_closeextattr;
   76 static vop_create_t     union_create;
   77 static vop_deleteextattr_t      union_deleteextattr;
   78 static vop_fsync_t      union_fsync;
   79 static vop_getacl_t     union_getacl;
   80 static vop_getattr_t    union_getattr;
   81 static vop_getextattr_t union_getextattr;
   82 static vop_inactive_t   union_inactive;
   83 static vop_ioctl_t      union_ioctl;
   84 static vop_lease_t      union_lease;
   85 static vop_link_t       union_link;
   86 static vop_listextattr_t        union_listextattr;
   87 static vop_lookup_t     union_lookup;
   88 static int      union_lookup1(struct vnode *udvp, struct vnode **dvp,
   89                                    struct vnode **vpp,
   90                                    struct componentname *cnp);
   91 static vop_mkdir_t      union_mkdir;
   92 static vop_mknod_t      union_mknod;
   93 static vop_open_t       union_open;
   94 static vop_openextattr_t        union_openextattr;
   95 static vop_pathconf_t   union_pathconf;
   96 static vop_print_t      union_print;
   97 static vop_read_t       union_read;
   98 static vop_readdir_t    union_readdir;
   99 static vop_readlink_t   union_readlink;
  100 static vop_getwritemount_t      union_getwritemount;
  101 static vop_reclaim_t    union_reclaim;
  102 static vop_remove_t     union_remove;
  103 static vop_rename_t     union_rename;
  104 static vop_rmdir_t      union_rmdir;
  105 static vop_poll_t       union_poll;
  106 static vop_setacl_t     union_setacl;
  107 static vop_setattr_t    union_setattr;
  108 static vop_setlabel_t   union_setlabel;
  109 static vop_setextattr_t union_setextattr;
  110 static vop_strategy_t   union_strategy;
  111 static vop_symlink_t    union_symlink;
  112 static vop_whiteout_t   union_whiteout;
  113 static vop_write_t      union_write;
  114 
  115 static __inline
  116 struct vnode *
  117 union_lock_upper(struct union_node *un, struct thread *td)
  118 {
  119         struct vnode *uppervp;
  120 
  121         if ((uppervp = un->un_uppervp) != NULL) {
  122                 VREF(uppervp);
  123                 vn_lock(uppervp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, td);
  124         }
  125         KASSERT((uppervp == NULL || vrefcnt(uppervp) > 0), ("uppervp usecount is 0"));
  126         return(uppervp);
  127 }
  128 
  129 static __inline
  130 void
  131 union_unlock_upper(struct vnode *uppervp, struct thread *td)
  132 {
  133         vput(uppervp);
  134 }
  135 
  136 static __inline
  137 struct vnode *
  138 union_lock_other(struct union_node *un, struct thread *td)
  139 {
  140         struct vnode *vp;
  141 
  142         if (un->un_uppervp != NULL) {
  143                 vp = union_lock_upper(un, td);
  144         } else if ((vp = un->un_lowervp) != NULL) {
  145                 VREF(vp);
  146                 vn_lock(vp, LK_EXCLUSIVE | LK_CANRECURSE | LK_RETRY, td);
  147         }
  148         return(vp);
  149 }
  150 
  151 static __inline
  152 void
  153 union_unlock_other(struct vnode *vp, struct thread *td)
  154 {
  155         vput(vp);
  156 }
  157 
  158 /*
  159  *      union_lookup:
  160  *
  161  *      udvp    must be exclusively locked on call and will remain 
  162  *              exclusively locked on return.  This is the mount point 
  163  *              for our filesystem.
  164  *
  165  *      dvp     Our base directory, locked and referenced.
  166  *              The passed dvp will be dereferenced and unlocked on return
  167  *              and a new dvp will be returned which is locked and 
  168  *              referenced in the same variable.
  169  *
  170  *      vpp     is filled in with the result if no error occured,
  171  *              locked and ref'd.
  172  *
  173  *              If an error is returned, *vpp is set to NULLVP.  If no
  174  *              error occurs, *vpp is returned with a reference and an
  175  *              exclusive lock.
  176  */
  177 
  178 static int
  179 union_lookup1(udvp, pdvp, vpp, cnp)
  180         struct vnode *udvp;
  181         struct vnode **pdvp;
  182         struct vnode **vpp;
  183         struct componentname *cnp;
  184 {
  185         int error;
  186         struct thread *td = cnp->cn_thread;
  187         struct vnode *dvp = *pdvp;
  188         struct vnode *tdvp;
  189         struct mount *mp;
  190 
  191         /*
  192          * If stepping up the directory tree, check for going
  193          * back across the mount point, in which case do what
  194          * lookup would do by stepping back down the mount
  195          * hierarchy.
  196          */
  197         if (cnp->cn_flags & ISDOTDOT) {
  198                 while ((dvp != udvp) && (dvp->v_vflag & VV_ROOT)) {
  199                         /*
  200                          * Don't do the NOCROSSMOUNT check
  201                          * at this level.  By definition,
  202                          * union fs deals with namespaces, not
  203                          * filesystems.
  204                          */
  205                         tdvp = dvp;
  206                         dvp = dvp->v_mount->mnt_vnodecovered;
  207                         VREF(dvp);
  208                         vput(tdvp);
  209                         vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, td);
  210                 }
  211         }
  212 
  213         /*
  214          * Set return dvp to be the upperdvp 'parent directory.
  215          */
  216         *pdvp = dvp;
  217 
  218         /*
  219          * If the VOP_LOOKUP() call generates an error, tdvp is invalid and
  220          * no changes will have been made to dvp, so we are set to return.
  221          */
  222 
  223         error = VOP_LOOKUP(dvp, &tdvp, cnp);
  224         if (error) {
  225                 UDEBUG(("dvp %p error %d flags %lx\n", dvp, error, cnp->cn_flags));
  226                 *vpp = NULL;
  227                 return (error);
  228         }
  229         UDEBUG(("parentdir %p result %p flag %lx\n", dvp, tdvp, cnp->cn_flags));
  230 
  231         /*
  232          * Lastly check if the current node is a mount point in
  233          * which case walk up the mount hierarchy making sure not to
  234          * bump into the root of the mount tree (ie. dvp != udvp).
  235          *
  236          * We use dvp as a temporary variable here, it is no longer related
  237          * to the dvp above.  However, we have to ensure that both *pdvp and
  238          * tdvp are locked on return.
  239          */
  240 
  241         dvp = tdvp;
  242         while (
  243             dvp != udvp && 
  244             (dvp->v_type == VDIR) &&
  245             (mp = dvp->v_mountedhere)
  246         ) {
  247                 int relock_pdvp = 0;
  248 
  249                 if (vfs_busy(mp, 0, 0, td))
  250                         continue;
  251 
  252                 if (dvp == *pdvp)
  253                         relock_pdvp = 1;
  254                 vput(dvp);
  255                 dvp = NULL;
  256                 error = VFS_ROOT(mp, LK_EXCLUSIVE, &dvp, td);
  257 
  258                 vfs_unbusy(mp, td);
  259 
  260                 if (relock_pdvp)
  261                         vn_lock(*pdvp, LK_EXCLUSIVE | LK_RETRY, td);
  262 
  263                 if (error) {
  264                         *vpp = NULL;
  265                         return (error);
  266                 }
  267         }
  268         *vpp = dvp;
  269         return (0);
  270 }
  271 
  272 static int
  273 union_lookup(ap)
  274         struct vop_lookup_args /* {
  275                 struct vnodeop_desc *a_desc;
  276                 struct vnode *a_dvp;
  277                 struct vnode **a_vpp;
  278                 struct componentname *a_cnp;
  279         } */ *ap;
  280 {
  281         int error;
  282         int uerror, lerror;
  283         struct vnode *uppervp, *lowervp;
  284         struct vnode *upperdvp, *lowerdvp;
  285         struct vnode *dvp = ap->a_dvp;          /* starting dir */
  286         struct union_node *dun = VTOUNION(dvp); /* associated union node */
  287         struct componentname *cnp = ap->a_cnp;
  288         struct thread *td = cnp->cn_thread;
  289         struct union_mount *um = MOUNTTOUNIONMOUNT(dvp->v_mount);
  290         struct ucred *saved_cred = NULL;
  291         int iswhiteout;
  292         struct vattr va;
  293 
  294         *ap->a_vpp = NULLVP;
  295 
  296         /*
  297          * Disallow write attempts to the filesystem mounted read-only.
  298          */
  299         if ((cnp->cn_flags & ISLASTCN) && 
  300             (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
  301             (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
  302                 return (EROFS);
  303         }
  304 
  305         /*
  306          * For any lookups we do, always return with the parent locked.
  307          */
  308         cnp->cn_flags |= LOCKPARENT;
  309 
  310         lowerdvp = dun->un_lowervp;
  311         uppervp = NULLVP;
  312         lowervp = NULLVP;
  313         iswhiteout = 0;
  314 
  315         uerror = ENOENT;
  316         lerror = ENOENT;
  317 
  318         /*
  319          * Get a private lock on uppervp and a reference, effectively 
  320          * taking it out of the union_node's control.
  321          *
  322          * We must lock upperdvp while holding our lock on dvp
  323          * to avoid a deadlock.
  324          */
  325         upperdvp = union_lock_upper(dun, td);
  326 
  327         /*
  328          * Do the lookup in the upper level.
  329          * If that level consumes additional pathnames,
  330          * then assume that something special is going
  331          * on and just return that vnode.
  332          */
  333         if (upperdvp != NULLVP) {
  334                 /*
  335                  * We do not have to worry about the DOTDOT case, we've
  336                  * already unlocked dvp.
  337                  */
  338                 UDEBUG(("A %p\n", upperdvp));
  339 
  340                 /*
  341                  * Do the lookup.   We must supply a locked and referenced
  342                  * upperdvp to the function and will get a new locked and
  343                  * referenced upperdvp back, with the old having been 
  344                  * dereferenced.
  345                  *
  346                  * If an error is returned, uppervp will be NULLVP.  If no
  347                  * error occurs, uppervp will be the locked and referenced.
  348                  * Return vnode, or possibly NULL, depending on what is being
  349                  * requested.  It is possible that the returned uppervp
  350                  * will be the same as upperdvp.
  351                  */
  352                 uerror = union_lookup1(um->um_uppervp, &upperdvp, &uppervp, cnp);
  353                 UDEBUG((
  354                     "uerror %d upperdvp %p %d/%d, uppervp %p ref=%d/lck=%d\n",
  355                     uerror,
  356                     upperdvp,
  357                     vrefcnt(upperdvp),
  358                     VOP_ISLOCKED(upperdvp, NULL),
  359                     uppervp,
  360                     (uppervp ? vrefcnt(uppervp) : -99),
  361                     (uppervp ? VOP_ISLOCKED(uppervp, NULL) : -99)
  362                 ));
  363 
  364                 /*
  365                  * Disallow write attempts to the filesystem mounted read-only.
  366                  */
  367                 if (uerror == EJUSTRETURN && (cnp->cn_flags & ISLASTCN) &&
  368                     (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
  369                     (cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME)) {
  370                         error = EROFS;
  371                         goto out;
  372                 }
  373 
  374                 /*
  375                  * Special case: If cn_consume != 0 then skip out.  The result
  376                  * of the lookup is transfered to our return variable.  If
  377                  * an error occured we have to throw away the results.
  378                  */
  379 
  380                 if (cnp->cn_consume != 0) {
  381                         if ((error = uerror) == 0) {
  382                                 *ap->a_vpp = uppervp;
  383                                 uppervp = NULL;
  384                         }
  385                         goto out;
  386                 }
  387 
  388                 /*
  389                  * Calculate whiteout, fall through.
  390                  */
  391 
  392                 if (uerror == ENOENT || uerror == EJUSTRETURN) {
  393                         if (cnp->cn_flags & ISWHITEOUT) {
  394                                 iswhiteout = 1;
  395                         } else if (lowerdvp != NULLVP) {
  396                                 int terror;
  397 
  398                                 terror = VOP_GETATTR(upperdvp, &va,
  399                                         cnp->cn_cred, cnp->cn_thread);
  400                                 if (terror == 0 && (va.va_flags & OPAQUE))
  401                                         iswhiteout = 1;
  402                         }
  403                 }
  404         }
  405 
  406         /*
  407          * In a similar way to the upper layer, do the lookup
  408          * in the lower layer.   This time, if there is some
  409          * component magic going on, then vput whatever we got
  410          * back from the upper layer and return the lower vnode
  411          * instead.
  412          */
  413 
  414         if (lowerdvp != NULLVP && !iswhiteout) {
  415                 int nameiop;
  416 
  417                 UDEBUG(("B %p\n", lowerdvp));
  418 
  419                 /*
  420                  * Force only LOOKUPs on the lower node, since
  421                  * we won't be making changes to it anyway.
  422                  */
  423                 nameiop = cnp->cn_nameiop;
  424                 cnp->cn_nameiop = LOOKUP;
  425                 if (um->um_op == UNMNT_BELOW) {
  426                         saved_cred = cnp->cn_cred;
  427                         cnp->cn_cred = um->um_cred;
  428                 }
  429 
  430                 /*
  431                  * We shouldn't have to worry about locking interactions
  432                  * between the lower layer and our union layer (w.r.t.
  433                  * `..' processing) because we don't futz with lowervp
  434                  * locks in the union-node instantiation code path.
  435                  *
  436                  * union_lookup1() requires lowervp to be locked on entry,
  437                  * and it will be unlocked on return.  The ref count will
  438                  * not change.  On return lowervp doesn't represent anything
  439                  * to us so we NULL it out.
  440                  */
  441                 VREF(lowerdvp);
  442                 vn_lock(lowerdvp, LK_EXCLUSIVE | LK_RETRY, td);
  443                 lerror = union_lookup1(um->um_lowervp, &lowerdvp, &lowervp, cnp);
  444                 if (lowerdvp == lowervp)
  445                         vrele(lowerdvp);
  446                 else
  447                         vput(lowerdvp);
  448                 lowerdvp = NULL;        /* lowerdvp invalid after vput */
  449 
  450                 if (um->um_op == UNMNT_BELOW)
  451                         cnp->cn_cred = saved_cred;
  452                 cnp->cn_nameiop = nameiop;
  453 
  454                 if (cnp->cn_consume != 0 || lerror == EACCES) {
  455                         if ((error = lerror) == 0) {
  456                                 *ap->a_vpp = lowervp;
  457                                 lowervp = NULL;
  458                         }
  459                         goto out;
  460                 }
  461         } else {
  462                 UDEBUG(("C %p\n", lowerdvp));
  463                 if ((cnp->cn_flags & ISDOTDOT) && dun->un_pvp != NULLVP) {
  464                         if ((lowervp = LOWERVP(dun->un_pvp)) != NULL) {
  465                                 VREF(lowervp);
  466                                 vn_lock(lowervp, LK_EXCLUSIVE | LK_RETRY, td);
  467                                 lerror = 0;
  468                         }
  469                 }
  470         }
  471 
  472         /*
  473          * Ok.  Now we have uerror, uppervp, upperdvp, lerror, and lowervp.
  474          *
  475          * 1. If both layers returned an error, select the upper layer.
  476          *
  477          * 2. If the upper layer failed and the bottom layer succeeded,
  478          *    two subcases occur:
  479          *
  480          *      a.  The bottom vnode is not a directory, in which case
  481          *          just return a new union vnode referencing an
  482          *          empty top layer and the existing bottom layer.
  483          *
  484          *      b.  The bottom vnode is a directory, in which case
  485          *          create a new directory in the top layer and
  486          *          and fall through to case 3.
  487          *
  488          * 3. If the top layer succeeded, then return a new union
  489          *    vnode referencing whatever the new top layer and
  490          *    whatever the bottom layer returned.
  491          */
  492 
  493         /* case 1. */
  494         if ((uerror != 0) && (lerror != 0)) {
  495                 error = uerror;
  496                 goto out;
  497         }
  498 
  499         /* case 2. */
  500         if (uerror != 0 /* && (lerror == 0) */ ) {
  501                 if (lowervp->v_type == VDIR) { /* case 2b. */
  502                         KASSERT(uppervp == NULL, ("uppervp unexpectedly non-NULL"));
  503                         /*
  504                          * Oops, uppervp has a problem, we may have to shadow.
  505                          */
  506                         uerror = union_mkshadow(um, upperdvp, cnp, &uppervp);
  507                         if (uerror) {
  508                                 error = uerror;
  509                                 goto out;
  510                         }
  511                 }
  512         }
  513 
  514         /*
  515          * Must call union_allocvp() with both the upper and lower vnodes
  516          * referenced and the upper vnode locked.   ap->a_vpp is returned 
  517          * referenced and locked.  lowervp, uppervp, and upperdvp are 
  518          * absorbed by union_allocvp() whether it succeeds or fails.
  519          *
  520          * upperdvp is the parent directory of uppervp which may be
  521          * different, depending on the path, from dvp->un_uppervp.  That's
  522          * why it is a separate argument.  Note that it must be unlocked.
  523          *
  524          * dvp must be locked on entry to the call and will be locked on
  525          * return.
  526          */
  527 
  528         if (uppervp && uppervp != upperdvp)
  529                 VOP_UNLOCK(uppervp, 0, td);
  530         if (lowervp)
  531                 VOP_UNLOCK(lowervp, 0, td);
  532         if (upperdvp)
  533                 VOP_UNLOCK(upperdvp, 0, td);
  534 
  535         error = union_allocvp(ap->a_vpp, dvp->v_mount, dvp, upperdvp, cnp,
  536                               uppervp, lowervp, 1);
  537 
  538         UDEBUG(("Create %p = %p %p refs=%d\n", *ap->a_vpp, uppervp, lowervp, (*ap->a_vpp) ? vrefcnt(*ap->a_vpp) : -99));
  539 
  540         uppervp = NULL;
  541         upperdvp = NULL;
  542         lowervp = NULL;
  543 
  544         /* 
  545          *      Termination Code
  546          *
  547          *      - put away any extra junk laying around.  Note that lowervp
  548          *        (if not NULL) will never be the same as *ap->a_vp and 
  549          *        neither will uppervp, because when we set that state we 
  550          *        NULL-out lowervp or uppervp.  On the otherhand, upperdvp
  551          *        may match uppervp or *ap->a_vpp.
  552          *
  553          *      - relock/unlock dvp if appropriate.
  554          */
  555 
  556 out:
  557         if (upperdvp) {
  558                 if (upperdvp == uppervp || upperdvp == *ap->a_vpp)
  559                         vrele(upperdvp);
  560                 else
  561                         vput(upperdvp);
  562         }
  563 
  564         if (uppervp)
  565                 vput(uppervp);
  566 
  567         if (lowervp)
  568                 vput(lowervp);
  569 
  570         UDEBUG(("Out %d vpp %p/%d lower %p upper %p\n", error, *ap->a_vpp,
  571                 ((*ap->a_vpp) ? vrefcnt(*ap->a_vpp) : -99),
  572                 lowervp, uppervp));
  573 
  574         if (error == 0 || error == EJUSTRETURN) {
  575                 if (cnp->cn_namelen == 1 &&
  576                     cnp->cn_nameptr[0] == '.' &&
  577                     *ap->a_vpp != dvp) {
  578 #ifdef  DIAGNOSTIC
  579                         vprint("union_lookup: vp", *ap->a_vpp);
  580                         vprint("union_lookup: dvp", dvp);
  581 #endif
  582                         panic("union_lookup returning . (%p) != startdir (%p)",
  583                             *ap->a_vpp, dvp);
  584                 }
  585         }
  586 
  587         return (error);
  588 }
  589 
  590 /*
  591  *      union_create:
  592  *
  593  * a_dvp is locked on entry and remains locked on return.  a_vpp is returned
  594  * locked if no error occurs, otherwise it is garbage.
  595  */
  596 
  597 static int
  598 union_create(ap)
  599         struct vop_create_args /* {
  600                 struct vnode *a_dvp;
  601                 struct vnode **a_vpp;
  602                 struct componentname *a_cnp;
  603                 struct vattr *a_vap;
  604         } */ *ap;
  605 {
  606         struct union_node *dun = VTOUNION(ap->a_dvp);
  607         struct componentname *cnp = ap->a_cnp;
  608         struct thread *td = cnp->cn_thread;
  609         struct vnode *dvp;
  610         int error = EROFS;
  611 
  612         if ((dvp = union_lock_upper(dun, td)) != NULL) {
  613                 struct vnode *vp;
  614                 struct mount *mp;
  615 
  616                 error = VOP_CREATE(dvp, &vp, cnp, ap->a_vap);
  617                 if (error == 0) {
  618                         mp = ap->a_dvp->v_mount;
  619                         VOP_UNLOCK(vp, 0, td);
  620                         UDEBUG(("ALLOCVP-1 FROM %p REFS %d\n", vp, vrefcnt(vp)));
  621                         error = union_allocvp(ap->a_vpp, mp, NULLVP, NULLVP,
  622                                 cnp, vp, NULLVP, 1);
  623                         UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vrefcnt(vp)));
  624                 }
  625                 union_unlock_upper(dvp, td);
  626         }
  627         return (error);
  628 }
  629 
  630 static int
  631 union_whiteout(ap)
  632         struct vop_whiteout_args /* {
  633                 struct vnode *a_dvp;
  634                 struct componentname *a_cnp;
  635                 int a_flags;
  636         } */ *ap;
  637 {
  638         struct union_node *un = VTOUNION(ap->a_dvp);
  639         struct componentname *cnp = ap->a_cnp;
  640         struct vnode *uppervp;
  641         int error;
  642 
  643         switch (ap->a_flags) {
  644         case CREATE:
  645         case DELETE:
  646                 uppervp = union_lock_upper(un, cnp->cn_thread);
  647                 if (uppervp != NULLVP) {
  648                         error = VOP_WHITEOUT(un->un_uppervp, cnp, ap->a_flags);
  649                         union_unlock_upper(uppervp, cnp->cn_thread);
  650                 } else
  651                         error = EOPNOTSUPP;
  652                 break;
  653         case LOOKUP:
  654                 error = EOPNOTSUPP;
  655                 break;
  656         default:
  657                 panic("union_whiteout: unknown op");
  658         }
  659         return (error);
  660 }
  661 
  662 /*
  663  *      union_mknod:
  664  *
  665  *      a_dvp is locked on entry and should remain locked on return.
  666  *      a_vpp is garbagre whether an error occurs or not.
  667  */
  668 
  669 static int
  670 union_mknod(ap)
  671         struct vop_mknod_args /* {
  672                 struct vnode *a_dvp;
  673                 struct vnode **a_vpp;
  674                 struct componentname *a_cnp;
  675                 struct vattr *a_vap;
  676         } */ *ap;
  677 {
  678         struct union_node *dun = VTOUNION(ap->a_dvp);
  679         struct componentname *cnp = ap->a_cnp;
  680         struct vnode *dvp;
  681         int error = EROFS;
  682 
  683         if ((dvp = union_lock_upper(dun, cnp->cn_thread)) != NULL) {
  684                 error = VOP_MKNOD(dvp, ap->a_vpp, cnp, ap->a_vap);
  685                 union_unlock_upper(dvp, cnp->cn_thread);
  686         }
  687         return (error);
  688 }
  689 
  690 /*
  691  *      union_open:
  692  *
  693  *      run open VOP.  When opening the underlying vnode we have to mimic
  694  *      vn_open().  What we *really* need to do to avoid screwups if the
  695  *      open semantics change is to call vn_open().  For example, ufs blows
  696  *      up if you open a file but do not vmio it prior to writing.
  697  */
  698 
  699 static int
  700 union_open(ap)
  701         struct vop_open_args /* {
  702                 struct vnodeop_desc *a_desc;
  703                 struct vnode *a_vp;
  704                 int a_mode;
  705                 struct ucred *a_cred;
  706                 struct thread *a_td;
  707         } */ *ap;
  708 {
  709         struct union_node *un = VTOUNION(ap->a_vp);
  710         struct vnode *tvp;
  711         int mode = ap->a_mode;
  712         struct ucred *cred = ap->a_cred;
  713         struct thread *td = ap->a_td;
  714         int error = 0;
  715         int tvpisupper = 1;
  716 
  717         /*
  718          * If there is an existing upper vp then simply open that.
  719          * The upper vp takes precedence over the lower vp.  When opening
  720          * a lower vp for writing copy it to the uppervp and then open the
  721          * uppervp.
  722          *
  723          * At the end of this section tvp will be left locked.
  724          */
  725         if ((tvp = union_lock_upper(un, td)) == NULLVP) {
  726                 /*
  727                  * If the lower vnode is being opened for writing, then
  728                  * copy the file contents to the upper vnode and open that,
  729                  * otherwise can simply open the lower vnode.
  730                  */
  731                 tvp = un->un_lowervp;
  732                 if ((ap->a_mode & FWRITE) && (tvp->v_type == VREG)) {
  733                         int docopy = !(mode & O_TRUNC);
  734                         error = union_copyup(un, docopy, cred, td);
  735                         tvp = union_lock_upper(un, td);
  736                 } else {
  737                         un->un_openl++;
  738                         VREF(tvp);
  739                         vn_lock(tvp, LK_EXCLUSIVE | LK_RETRY, td);
  740                         tvpisupper = 0;
  741                 }
  742         }
  743 
  744         /*
  745          * We are holding the correct vnode, open it.
  746          */
  747 
  748         if (error == 0)
  749                 error = VOP_OPEN(tvp, mode, cred, td, -1);
  750         if (error == 0)
  751                 ap->a_vp->v_object = tvp->v_object;
  752         /*
  753          * Release any locks held.
  754          */
  755         if (tvpisupper) {
  756                 if (tvp)
  757                         union_unlock_upper(tvp, td);
  758         } else {
  759                 vput(tvp);
  760         }
  761         return (error);
  762 }
  763 
  764 /*
  765  *      union_close:
  766  *
  767  *      It is unclear whether a_vp is passed locked or unlocked.  Whatever
  768  *      the case we do not change it.
  769  */
  770 
  771 static int
  772 union_close(ap)
  773         struct vop_close_args /* {
  774                 struct vnode *a_vp;
  775                 int  a_fflag;
  776                 struct ucred *a_cred;
  777                 struct thread *a_td;
  778         } */ *ap;
  779 {
  780         struct union_node *un = VTOUNION(ap->a_vp);
  781         struct vnode *vp;
  782 
  783         if ((vp = un->un_uppervp) == NULLVP) {
  784 #ifdef UNION_DIAGNOSTIC
  785                 if (un->un_openl <= 0)
  786                         panic("union: un_openl cnt");
  787 #endif
  788                 --un->un_openl;
  789                 vp = un->un_lowervp;
  790         }
  791         ap->a_vp = vp;
  792         return (VOP_CLOSE_AP(ap));
  793 }
  794 
  795 /*
  796  * Check access permission on the union vnode.
  797  * The access check being enforced is to check
  798  * against both the underlying vnode, and any
  799  * copied vnode.  This ensures that no additional
  800  * file permissions are given away simply because
  801  * the user caused an implicit file copy.
  802  */
  803 static int
  804 union_access(ap)
  805         struct vop_access_args /* {
  806                 struct vnodeop_desc *a_desc;
  807                 struct vnode *a_vp;
  808                 int a_mode;
  809                 struct ucred *a_cred;
  810                 struct thread *a_td;
  811         } */ *ap;
  812 {
  813         struct union_node *un = VTOUNION(ap->a_vp);
  814         struct thread *td = ap->a_td;
  815         int error = EACCES;
  816         struct vnode *vp;
  817 
  818         /*
  819          * Disallow write attempts on filesystems mounted read-only.
  820          */
  821         if ((ap->a_mode & VWRITE) && 
  822             (ap->a_vp->v_mount->mnt_flag & MNT_RDONLY)) {
  823                 switch (ap->a_vp->v_type) {
  824                 case VREG: 
  825                 case VDIR:
  826                 case VLNK:
  827                         return (EROFS);
  828                 default:
  829                         break;
  830                 }
  831         }
  832 
  833         if ((vp = union_lock_upper(un, td)) != NULLVP) {
  834                 ap->a_vp = vp;
  835                 error = VOP_ACCESS_AP(ap);
  836                 union_unlock_upper(vp, td);
  837                 return(error);
  838         }
  839 
  840         if ((vp = un->un_lowervp) != NULLVP) {
  841                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
  842                 ap->a_vp = vp;
  843 
  844                 /*
  845                  * Remove VWRITE from a_mode if our mount point is RW, because
  846                  * we want to allow writes and lowervp may be read-only.
  847                  */
  848                 if ((un->un_vnode->v_mount->mnt_flag & MNT_RDONLY) == 0)
  849                         ap->a_mode &= ~VWRITE;
  850 
  851                 error = VOP_ACCESS_AP(ap);
  852                 if (error == 0) {
  853                         struct union_mount *um;
  854 
  855                         um = MOUNTTOUNIONMOUNT(un->un_vnode->v_mount);
  856 
  857                         if (um->um_op == UNMNT_BELOW) {
  858                                 ap->a_cred = um->um_cred;
  859                                 error = VOP_ACCESS_AP(ap);
  860                         }
  861                 }
  862                 VOP_UNLOCK(vp, 0, td);
  863         }
  864         return(error);
  865 }
  866 
  867 /*
  868  * We handle getattr only to change the fsid and
  869  * track object sizes
  870  *
  871  * It's not clear whether VOP_GETATTR is to be
  872  * called with the vnode locked or not.  stat() calls
  873  * it with (vp) locked, and fstat() calls it with
  874  * (vp) unlocked. 
  875  *
  876  * Because of this we cannot use our normal locking functions
  877  * if we do not intend to lock the main a_vp node.  At the moment
  878  * we are running without any specific locking at all, but beware
  879  * to any programmer that care must be taken if locking is added
  880  * to this function.
  881  */
  882 
  883 static int
  884 union_getattr(ap)
  885         struct vop_getattr_args /* {
  886                 struct vnode *a_vp;
  887                 struct vattr *a_vap;
  888                 struct ucred *a_cred;
  889                 struct thread *a_td;
  890         } */ *ap;
  891 {
  892         int error;
  893         struct union_node *un = VTOUNION(ap->a_vp);
  894         struct union_mount *um = MOUNTTOUNIONMOUNT(ap->a_vp->v_mount);
  895         struct vnode *vp;
  896         struct vattr *vap;
  897         struct vattr va;
  898 
  899         /*
  900          * Some programs walk the filesystem hierarchy by counting
  901          * links to directories to avoid stat'ing all the time.
  902          * This means the link count on directories needs to be "correct".
  903          * The only way to do that is to call getattr on both layers
  904          * and fix up the link count.  The link count will not necessarily
  905          * be accurate but will be large enough to defeat the tree walkers.
  906          */
  907 
  908         vap = ap->a_vap;
  909 
  910         if ((vp = un->un_uppervp) != NULLVP) {
  911                 error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_td);
  912                 if (error)
  913                         return (error);
  914                 /* XXX isn't this dangerous without a lock? */
  915                 union_newsize(ap->a_vp, vap->va_size, VNOVAL);
  916         }
  917 
  918         if (vp == NULLVP) {
  919                 vp = un->un_lowervp;
  920         } else if (vp->v_type == VDIR && un->un_lowervp != NULLVP) {
  921                 vp = un->un_lowervp;
  922                 vap = &va;
  923         } else {
  924                 vp = NULLVP;
  925         }
  926 
  927         if (vp != NULLVP) {
  928                 error = VOP_GETATTR(vp, vap, ap->a_cred, ap->a_td);
  929                 if (error)
  930                         return (error);
  931                 /* XXX isn't this dangerous without a lock? */
  932                 union_newsize(ap->a_vp, VNOVAL, vap->va_size);
  933         }
  934 
  935         if (ap->a_vap->va_fsid == um->um_upperdev)
  936                 ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
  937 
  938         if ((vap != ap->a_vap) && (vap->va_type == VDIR))
  939                 ap->a_vap->va_nlink += vap->va_nlink;
  940         return (0);
  941 }
  942 
  943 static int
  944 union_setattr(ap)
  945         struct vop_setattr_args /* {
  946                 struct vnode *a_vp;
  947                 struct vattr *a_vap;
  948                 struct ucred *a_cred;
  949                 struct thread *a_td;
  950         } */ *ap;
  951 {
  952         struct union_node *un = VTOUNION(ap->a_vp);
  953         struct thread *td = ap->a_td;
  954         struct vattr *vap = ap->a_vap;
  955         struct vnode *uppervp;
  956         int error;
  957 
  958         /*
  959          * Disallow write attempts on filesystems mounted read-only.
  960          */
  961         if ((ap->a_vp->v_mount->mnt_flag & MNT_RDONLY) &&
  962             (vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
  963              vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
  964              vap->va_mtime.tv_sec != VNOVAL || 
  965              vap->va_mode != (mode_t)VNOVAL)) {
  966                 return (EROFS);
  967         }
  968 
  969         /*
  970          * Handle case of truncating lower object to zero size
  971          * by creating a zero length upper object.  This is to
  972          * handle the case of open with O_TRUNC and O_CREAT.
  973          */
  974         if (un->un_uppervp == NULLVP && (un->un_lowervp->v_type == VREG)) {
  975                 error = union_copyup(un, (ap->a_vap->va_size != 0),
  976                             ap->a_cred, ap->a_td);
  977                 if (error)
  978                         return (error);
  979         }
  980 
  981         /*
  982          * Try to set attributes in upper layer,
  983          * otherwise return read-only filesystem error.
  984          */
  985         error = EROFS;
  986         if ((uppervp = union_lock_upper(un, td)) != NULLVP) {
  987                 error = VOP_SETATTR(un->un_uppervp, ap->a_vap,
  988                                         ap->a_cred, ap->a_td);
  989                 if ((error == 0) && (ap->a_vap->va_size != VNOVAL))
  990                         union_newsize(ap->a_vp, ap->a_vap->va_size, VNOVAL);
  991                 union_unlock_upper(uppervp, td);
  992         }
  993         return (error);
  994 }
  995 
  996 static int
  997 union_read(ap)
  998         struct vop_read_args /* {
  999                 struct vnode *a_vp;
 1000                 struct uio *a_uio;
 1001                 int  a_ioflag;
 1002                 struct ucred *a_cred;
 1003         } */ *ap;
 1004 {
 1005         struct union_node *un = VTOUNION(ap->a_vp);
 1006         struct thread *td = ap->a_uio->uio_td;
 1007         struct vnode *uvp;
 1008         int error;
 1009 
 1010         uvp = union_lock_other(un, td);
 1011         KASSERT(uvp != NULL, ("union_read: backing vnode missing!"));
 1012 
 1013         error = VOP_READ(uvp, ap->a_uio, ap->a_ioflag, ap->a_cred);
 1014         union_unlock_other(uvp, td);
 1015 
 1016         /*
 1017          * XXX
 1018          * Perhaps the size of the underlying object has changed under
 1019          * our feet.  Take advantage of the offset information present
 1020          * in the uio structure.
 1021          */
 1022         if (error == 0) {
 1023                 struct union_node *un = VTOUNION(ap->a_vp);
 1024                 off_t cur = ap->a_uio->uio_offset;
 1025 
 1026                 if (uvp == un->un_uppervp) {
 1027                         if (cur > un->un_uppersz)
 1028                                 union_newsize(ap->a_vp, cur, VNOVAL);
 1029                 } else {
 1030                         if (cur > un->un_lowersz)
 1031                                 union_newsize(ap->a_vp, VNOVAL, cur);
 1032                 }
 1033         }
 1034         return (error);
 1035 }
 1036 
 1037 static int
 1038 union_write(ap)
 1039         struct vop_write_args /* {
 1040                 struct vnode *a_vp;
 1041                 struct uio *a_uio;
 1042                 int  a_ioflag;
 1043                 struct ucred *a_cred;
 1044         } */ *ap;
 1045 {
 1046         struct union_node *un = VTOUNION(ap->a_vp);
 1047         struct thread *td = ap->a_uio->uio_td;
 1048         struct vnode *uppervp;
 1049         int error;
 1050 
 1051         if ((uppervp = union_lock_upper(un, td)) == NULLVP)
 1052                 panic("union: missing upper layer in write");
 1053 
 1054         error = VOP_WRITE(uppervp, ap->a_uio, ap->a_ioflag, ap->a_cred);
 1055 
 1056         /*
 1057          * The size of the underlying object may be changed by the
 1058          * write.
 1059          */
 1060         if (error == 0) {
 1061                 off_t cur = ap->a_uio->uio_offset;
 1062 
 1063                 if (cur > un->un_uppersz)
 1064                         union_newsize(ap->a_vp, cur, VNOVAL);
 1065         }
 1066         union_unlock_upper(uppervp, td);
 1067         return (error);
 1068 }
 1069 
 1070 static int
 1071 union_lease(ap)
 1072         struct vop_lease_args /* {
 1073                 struct vnode *a_vp;
 1074                 struct thread *a_td;
 1075                 struct ucred *a_cred;
 1076                 int a_flag;
 1077         } */ *ap;
 1078 {
 1079         struct vnode *ovp = OTHERVP(ap->a_vp);
 1080 
 1081         ap->a_vp = ovp;
 1082         return (VOP_LEASE_AP(ap));
 1083 }
 1084 
 1085 static int
 1086 union_ioctl(ap)
 1087         struct vop_ioctl_args /* {
 1088                 struct vnode *a_vp;
 1089                 u_long  a_command;
 1090                 caddr_t  a_data;
 1091                 int  a_fflag;
 1092                 struct ucred *a_cred;
 1093                 struct thread *a_td;
 1094         } */ *ap;
 1095 {
 1096         struct vnode *ovp = OTHERVP(ap->a_vp);
 1097 
 1098         ap->a_vp = ovp;
 1099         return (VOP_IOCTL_AP(ap));
 1100 }
 1101 
 1102 static int
 1103 union_poll(ap)
 1104         struct vop_poll_args /* {
 1105                 struct vnode *a_vp;
 1106                 int  a_events;
 1107                 struct ucred *a_cred;
 1108                 struct thread *a_td;
 1109         } */ *ap;
 1110 {
 1111         struct vnode *ovp = OTHERVP(ap->a_vp);
 1112 
 1113         ap->a_vp = ovp;
 1114         return (VOP_POLL_AP(ap));
 1115 }
 1116 
 1117 static int
 1118 union_fsync(ap)
 1119         struct vop_fsync_args /* {
 1120                 struct vnode *a_vp;
 1121                 struct ucred *a_cred;
 1122                 int  a_waitfor;
 1123                 struct thread *a_td;
 1124         } */ *ap;
 1125 {
 1126         int error = 0;
 1127         struct thread *td = ap->a_td;
 1128         struct vnode *targetvp;
 1129         struct union_node *un = VTOUNION(ap->a_vp);
 1130 
 1131         if ((targetvp = union_lock_other(un, td)) != NULLVP) {
 1132                 error = VOP_FSYNC(targetvp, ap->a_waitfor, td);
 1133                 union_unlock_other(targetvp, td);
 1134         }
 1135 
 1136         return (error);
 1137 }
 1138 
 1139 /*
 1140  *      union_remove:
 1141  *
 1142  *      Remove the specified cnp.  The dvp and vp are passed to us locked
 1143  *      and must remain locked on return.
 1144  */
 1145 
 1146 static int
 1147 union_remove(ap)
 1148         struct vop_remove_args /* {
 1149                 struct vnode *a_dvp;
 1150                 struct vnode *a_vp;
 1151                 struct componentname *a_cnp;
 1152         } */ *ap;
 1153 {
 1154         struct union_node *dun = VTOUNION(ap->a_dvp);
 1155         struct union_node *un = VTOUNION(ap->a_vp);
 1156         struct componentname *cnp = ap->a_cnp;
 1157         struct thread *td = cnp->cn_thread;
 1158         struct vnode *uppervp;
 1159         struct vnode *upperdvp;
 1160         int error;
 1161 
 1162         if ((upperdvp = union_lock_upper(dun, td)) == NULLVP)
 1163                 panic("union remove: null upper vnode");
 1164 
 1165         if ((uppervp = union_lock_upper(un, td)) != NULLVP) {
 1166                 if (union_dowhiteout(un, cnp->cn_cred, td))
 1167                         cnp->cn_flags |= DOWHITEOUT;
 1168                 if (cnp->cn_flags & DOWHITEOUT)         /* XXX fs corruption */
 1169                         error = EOPNOTSUPP;
 1170                 else
 1171                         error = VOP_REMOVE(upperdvp, uppervp, cnp);
 1172                 if (!error)
 1173                         union_removed_upper(un);
 1174                 union_unlock_upper(uppervp, td);
 1175         } else {
 1176                 error = union_mkwhiteout(
 1177                             MOUNTTOUNIONMOUNT(ap->a_dvp->v_mount),
 1178                             upperdvp, ap->a_cnp, un->un_path);
 1179         }
 1180         union_unlock_upper(upperdvp, td);
 1181         return (error);
 1182 }
 1183 
 1184 /*
 1185  *      union_link:
 1186  *
 1187  *      tdvp and vp will be locked on entry.
 1188  *      tdvp and vp should remain locked on return.
 1189  */
 1190 
 1191 static int
 1192 union_link(ap)
 1193         struct vop_link_args /* {
 1194                 struct vnode *a_tdvp;
 1195                 struct vnode *a_vp;
 1196                 struct componentname *a_cnp;
 1197         } */ *ap;
 1198 {
 1199         struct componentname *cnp = ap->a_cnp;
 1200         struct thread *td = cnp->cn_thread;
 1201         struct union_node *dun = VTOUNION(ap->a_tdvp);
 1202         struct vnode *vp;
 1203         struct vnode *tdvp;
 1204         int error = 0;
 1205 
 1206         if (ap->a_tdvp->v_op != ap->a_vp->v_op) {
 1207                 vp = ap->a_vp;
 1208         } else {
 1209                 struct union_node *tun = VTOUNION(ap->a_vp);
 1210 
 1211                 if (tun->un_uppervp == NULLVP) {
 1212 #if 0
 1213                         if (dun->un_uppervp == tun->un_dirvp) {
 1214                                 if (dun->un_flags & UN_ULOCK) {
 1215                                         dun->un_flags &= ~UN_ULOCK;
 1216                                         VOP_UNLOCK(dun->un_uppervp, 0, td);
 1217                                 }
 1218                         }
 1219 #endif
 1220                         error = union_copyup(tun, 1, cnp->cn_cred, td);
 1221 #if 0
 1222                         if (dun->un_uppervp == tun->un_dirvp) {
 1223                                 vn_lock(dun->un_uppervp,
 1224                                             LK_EXCLUSIVE | LK_RETRY, td);
 1225                                 dun->un_flags |= UN_ULOCK;
 1226                         }
 1227 #endif
 1228                         if (error)
 1229                                 return (error);
 1230                 }
 1231                 vp = tun->un_uppervp;
 1232                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1233         }
 1234 
 1235         /*
 1236          * Make sure upper is locked, then unlock the union directory we were 
 1237          * called with to avoid a deadlock while we are calling VOP_LINK() on 
 1238          * the upper (with tdvp locked and vp not locked).  Our ap->a_tdvp
 1239          * is expected to be locked on return.
 1240          */
 1241 
 1242         if ((tdvp = union_lock_upper(dun, td)) == NULLVP)
 1243                 return (EROFS);
 1244 
 1245         VOP_UNLOCK(ap->a_tdvp, 0, td);          /* unlock calling node */
 1246         error = VOP_LINK(tdvp, vp, cnp);        /* call link on upper */
 1247 
 1248         /*
 1249          * Unlock tun->un_uppervp if we locked it above.
 1250          */
 1251         if (ap->a_tdvp->v_op == ap->a_vp->v_op)
 1252                 VOP_UNLOCK(vp, 0, td);
 1253         /*
 1254          * We have to unlock tdvp prior to relocking our calling node in
 1255          * order to avoid a deadlock.  We also have to unlock ap->a_vp
 1256          * before relocking the directory, but then we have to relock
 1257          * ap->a_vp as our caller expects.
 1258          */
 1259         VOP_UNLOCK(ap->a_vp, 0, td);
 1260         union_unlock_upper(tdvp, td);
 1261         vn_lock(ap->a_tdvp, LK_EXCLUSIVE | LK_RETRY, td);
 1262         vn_lock(ap->a_vp, LK_EXCLUSIVE | LK_RETRY, td);
 1263         return (error);
 1264 }
 1265 
 1266 static int
 1267 union_rename(ap)
 1268         struct vop_rename_args  /* {
 1269                 struct vnode *a_fdvp;
 1270                 struct vnode *a_fvp;
 1271                 struct componentname *a_fcnp;
 1272                 struct vnode *a_tdvp;
 1273                 struct vnode *a_tvp;
 1274                 struct componentname *a_tcnp;
 1275         } */ *ap;
 1276 {
 1277         int error;
 1278         struct vnode *fdvp = ap->a_fdvp;
 1279         struct vnode *fvp = ap->a_fvp;
 1280         struct vnode *tdvp = ap->a_tdvp;
 1281         struct vnode *tvp = ap->a_tvp;
 1282 
 1283         /*
 1284          * Figure out what fdvp to pass to our upper or lower vnode.  If we
 1285          * replace the fdvp, release the original one and ref the new one.
 1286          */
 1287 
 1288         if (fdvp->v_op == &union_vnodeops) {    /* always true */
 1289                 struct union_node *un = VTOUNION(fdvp);
 1290                 if (un->un_uppervp == NULLVP) {
 1291                         /*
 1292                          * this should never happen in normal
 1293                          * operation but might if there was
 1294                          * a problem creating the top-level shadow
 1295                          * directory.
 1296                          */
 1297                         error = EXDEV;
 1298                         goto bad;
 1299                 }
 1300                 fdvp = un->un_uppervp;
 1301                 VREF(fdvp);
 1302                 vrele(ap->a_fdvp);
 1303         }
 1304 
 1305         /*
 1306          * Figure out what fvp to pass to our upper or lower vnode.  If we
 1307          * replace the fvp, release the original one and ref the new one.
 1308          */
 1309 
 1310         if (fvp->v_op == &union_vnodeops) {     /* always true */
 1311                 struct union_node *un = VTOUNION(fvp);
 1312 #if 0
 1313                 struct union_mount *um = MOUNTTOUNIONMOUNT(fvp->v_mount);
 1314 #endif
 1315 
 1316                 if (un->un_uppervp == NULLVP) {
 1317                         switch(fvp->v_type) {
 1318                         case VREG:
 1319                                 vn_lock(un->un_vnode, LK_EXCLUSIVE | LK_RETRY, ap->a_fcnp->cn_thread);
 1320                                 error = union_copyup(un, 1, ap->a_fcnp->cn_cred, ap->a_fcnp->cn_thread);
 1321                                 VOP_UNLOCK(un->un_vnode, 0, ap->a_fcnp->cn_thread);
 1322                                 if (error)
 1323                                         goto bad;
 1324                                 break;
 1325                         case VDIR:
 1326                                 /*
 1327                                  * XXX not yet.
 1328                                  *
 1329                                  * There is only one way to rename a directory
 1330                                  * based in the lowervp, and that is to copy
 1331                                  * the entire directory hierarchy.  Otherwise
 1332                                  * it would not last across a reboot.
 1333                                  */
 1334 #if 0
 1335                                 vrele(fvp);
 1336                                 fvp = NULL;
 1337                                 vn_lock(fdvp, LK_EXCLUSIVE | LK_RETRY, ap->a_fcnp->cn_thread);
 1338                                 error = union_mkshadow(um, fdvp, 
 1339                                             ap->a_fcnp, &un->un_uppervp);
 1340                                 VOP_UNLOCK(fdvp, 0, ap->a_fcnp->cn_thread);
 1341                                 if (un->un_uppervp)
 1342                                         VOP_UNLOCK(un->un_uppervp, 0, ap->a_fcnp->cn_thread);
 1343                                 if (error)
 1344                                         goto bad;
 1345                                 break;
 1346 #endif
 1347                         default:
 1348                                 error = EXDEV;
 1349                                 goto bad;
 1350                         }
 1351                 }
 1352 
 1353                 if (un->un_lowervp != NULLVP)
 1354                         ap->a_fcnp->cn_flags |= DOWHITEOUT;
 1355                 fvp = un->un_uppervp;
 1356                 VREF(fvp);
 1357                 vrele(ap->a_fvp);
 1358         }
 1359 
 1360         /*
 1361          * Figure out what tdvp (destination directory) to pass to the
 1362          * lower level.  If we replace it with uppervp, we need to vput the 
 1363          * old one.  The exclusive lock is transfered to what we will pass
 1364          * down in the VOP_RENAME() and we replace uppervp with a simple
 1365          * reference.
 1366          */
 1367 
 1368         if (tdvp->v_op == &union_vnodeops) {
 1369                 struct union_node *un = VTOUNION(tdvp);
 1370 
 1371                 if (un->un_uppervp == NULLVP) {
 1372                         /*
 1373                          * This should never happen in normal
 1374                          * operation but might if there was
 1375                          * a problem creating the top-level shadow
 1376                          * directory.
 1377                          */
 1378                         error = EXDEV;
 1379                         goto bad;
 1380                 }
 1381 
 1382                 /*
 1383                  * New tdvp is a lock and reference on uppervp.
 1384                  * Put away the old tdvp.
 1385                  */
 1386                 tdvp = union_lock_upper(un, ap->a_tcnp->cn_thread);
 1387                 vput(ap->a_tdvp);
 1388         }
 1389 
 1390         /*
 1391          * Figure out what tvp (destination file) to pass to the
 1392          * lower level.
 1393          *
 1394          * If the uppervp file does not exist, put away the (wrong)
 1395          * file and change tvp to NULL.
 1396          */
 1397 
 1398         if (tvp != NULLVP && tvp->v_op == &union_vnodeops) {
 1399                 struct union_node *un = VTOUNION(tvp);
 1400 
 1401                 tvp = union_lock_upper(un, ap->a_tcnp->cn_thread);
 1402                 vput(ap->a_tvp);
 1403                 /* note: tvp may be NULL */
 1404         }
 1405 
 1406         /*
 1407          * VOP_RENAME() releases/vputs prior to returning, so we have no
 1408          * cleanup to do.
 1409          */
 1410 
 1411         return (VOP_RENAME(fdvp, fvp, ap->a_fcnp, tdvp, tvp, ap->a_tcnp));
 1412 
 1413         /*
 1414          * Error.  We still have to release / vput the various elements.
 1415          */
 1416 
 1417 bad:
 1418         vrele(fdvp);
 1419         if (fvp)
 1420                 vrele(fvp);
 1421         vput(tdvp);
 1422         if (tvp != NULLVP) {
 1423                 if (tvp != tdvp)
 1424                         vput(tvp);
 1425                 else
 1426                         vrele(tvp);
 1427         }
 1428         return (error);
 1429 }
 1430 
 1431 static int
 1432 union_mkdir(ap)
 1433         struct vop_mkdir_args /* {
 1434                 struct vnode *a_dvp;
 1435                 struct vnode **a_vpp;
 1436                 struct componentname *a_cnp;
 1437                 struct vattr *a_vap;
 1438         } */ *ap;
 1439 {
 1440         struct union_node *dun = VTOUNION(ap->a_dvp);
 1441         struct componentname *cnp = ap->a_cnp;
 1442         struct thread *td = cnp->cn_thread;
 1443         struct vnode *upperdvp;
 1444         int error = EROFS;
 1445 
 1446         if ((upperdvp = union_lock_upper(dun, td)) != NULLVP) {
 1447                 struct vnode *vp;
 1448 
 1449                 error = VOP_MKDIR(upperdvp, &vp, cnp, ap->a_vap);
 1450                 union_unlock_upper(upperdvp, td);
 1451 
 1452                 if (error == 0) {
 1453                         VOP_UNLOCK(vp, 0, td);
 1454                         UDEBUG(("ALLOCVP-2 FROM %p REFS %d\n", vp, vrefcnt(vp)));
 1455                         error = union_allocvp(ap->a_vpp, ap->a_dvp->v_mount,
 1456                                 ap->a_dvp, NULLVP, cnp, vp, NULLVP, 1);
 1457                         UDEBUG(("ALLOCVP-2B FROM %p REFS %d\n", *ap->a_vpp, vrefcnt(vp)));
 1458                 }
 1459         }
 1460         return (error);
 1461 }
 1462 
 1463 static int
 1464 union_rmdir(ap)
 1465         struct vop_rmdir_args /* {
 1466                 struct vnode *a_dvp;
 1467                 struct vnode *a_vp;
 1468                 struct componentname *a_cnp;
 1469         } */ *ap;
 1470 {
 1471         struct union_node *dun = VTOUNION(ap->a_dvp);
 1472         struct union_node *un = VTOUNION(ap->a_vp);
 1473         struct componentname *cnp = ap->a_cnp;
 1474         struct thread *td = cnp->cn_thread;
 1475         struct vnode *upperdvp;
 1476         struct vnode *uppervp;
 1477         int error;
 1478 
 1479         if ((upperdvp = union_lock_upper(dun, td)) == NULLVP)
 1480                 panic("union rmdir: null upper vnode");
 1481 
 1482         if ((uppervp = union_lock_upper(un, td)) != NULLVP) {
 1483                 if (union_dowhiteout(un, cnp->cn_cred, td))
 1484                         cnp->cn_flags |= DOWHITEOUT;
 1485                 if (cnp->cn_flags & DOWHITEOUT)         /* XXX fs corruption */
 1486                         error = EOPNOTSUPP;
 1487                 else
 1488                         error = VOP_RMDIR(upperdvp, uppervp, ap->a_cnp);
 1489                 if (!error)
 1490                         union_removed_upper(un);
 1491                 union_unlock_upper(uppervp, td);
 1492         } else {
 1493                 error = union_mkwhiteout(
 1494                             MOUNTTOUNIONMOUNT(ap->a_dvp->v_mount),
 1495                             dun->un_uppervp, ap->a_cnp, un->un_path);
 1496         }
 1497         union_unlock_upper(upperdvp, td);
 1498         return (error);
 1499 }
 1500 
 1501 /*
 1502  *      union_symlink:
 1503  *
 1504  *      dvp is locked on entry and remains locked on return.  a_vpp is garbage
 1505  *      (unused).
 1506  */
 1507 
 1508 static int
 1509 union_symlink(ap)
 1510         struct vop_symlink_args /* {
 1511                 struct vnode *a_dvp;
 1512                 struct vnode **a_vpp;
 1513                 struct componentname *a_cnp;
 1514                 struct vattr *a_vap;
 1515                 char *a_target;
 1516         } */ *ap;
 1517 {
 1518         struct union_node *dun = VTOUNION(ap->a_dvp);
 1519         struct componentname *cnp = ap->a_cnp;
 1520         struct thread *td = cnp->cn_thread;
 1521         struct vnode *dvp;
 1522         int error = EROFS;
 1523 
 1524         if ((dvp = union_lock_upper(dun, td)) != NULLVP) {
 1525                 error = VOP_SYMLINK(dvp, ap->a_vpp, cnp, ap->a_vap,
 1526                             ap->a_target);
 1527                 union_unlock_upper(dvp, td);
 1528         }
 1529         return (error);
 1530 }
 1531 
 1532 /*
 1533  * union_readdir ()works in concert with getdirentries() and
 1534  * readdir(3) to provide a list of entries in the unioned
 1535  * directories.  getdirentries()  is responsible for walking
 1536  * down the union stack.  readdir(3) is responsible for
 1537  * eliminating duplicate names from the returned data stream.
 1538  */
 1539 static int
 1540 union_readdir(ap)
 1541         struct vop_readdir_args /* {
 1542                 struct vnode *a_vp;
 1543                 struct uio *a_uio;
 1544                 struct ucred *a_cred;
 1545                 int *a_eofflag;
 1546                 u_long *a_cookies;
 1547                 int a_ncookies;
 1548         } */ *ap;
 1549 {
 1550         struct union_node *un = VTOUNION(ap->a_vp);
 1551         struct thread *td = ap->a_uio->uio_td;
 1552         struct vnode *uvp;
 1553         int error = 0;
 1554 
 1555         if ((uvp = union_lock_upper(un, td)) != NULLVP) {
 1556                 ap->a_vp = uvp;
 1557                 error = VOP_READDIR_AP(ap);
 1558                 union_unlock_upper(uvp, td);
 1559         }
 1560         return(error);
 1561 }
 1562 
 1563 static int
 1564 union_readlink(ap)
 1565         struct vop_readlink_args /* {
 1566                 struct vnode *a_vp;
 1567                 struct uio *a_uio;
 1568                 struct ucred *a_cred;
 1569         } */ *ap;
 1570 {
 1571         int error;
 1572         struct union_node *un = VTOUNION(ap->a_vp);
 1573         struct uio *uio = ap->a_uio;
 1574         struct thread *td = uio->uio_td;
 1575         struct vnode *vp;
 1576 
 1577         vp = union_lock_other(un, td);
 1578         KASSERT(vp != NULL, ("union_readlink: backing vnode missing!"));
 1579 
 1580         ap->a_vp = vp;
 1581         error = VOP_READLINK_AP(ap);
 1582         union_unlock_other(vp, td);
 1583 
 1584         return (error);
 1585 }
 1586 
 1587 static int
 1588 union_getwritemount(ap)
 1589         struct vop_getwritemount_args /* {
 1590                 struct vnode *a_vp;
 1591                 struct mount **a_mpp;
 1592         } */ *ap;
 1593 {
 1594         struct vnode *vp = ap->a_vp;
 1595         struct vnode *uvp = UPPERVP(vp);
 1596 
 1597         if (uvp == NULL) {
 1598                 VI_LOCK(vp);
 1599                 if (vp->v_iflag & VI_FREE) {
 1600                         VI_UNLOCK(vp);
 1601                         return (EOPNOTSUPP);
 1602                 }
 1603                 VI_UNLOCK(vp);
 1604                 return (EACCES);
 1605         }
 1606         return(VOP_GETWRITEMOUNT(uvp, ap->a_mpp));
 1607 }
 1608 
 1609 /*
 1610  *      union_inactive:
 1611  *
 1612  *      Called with the vnode locked.  We are expected to unlock the vnode.
 1613  */
 1614 
 1615 static int
 1616 union_inactive(ap)
 1617         struct vop_inactive_args /* {
 1618                 struct vnode *a_vp;
 1619                 struct thread *a_td;
 1620         } */ *ap;
 1621 {
 1622         struct vnode *vp = ap->a_vp;
 1623         struct union_node *un = VTOUNION(vp);
 1624 
 1625         /*
 1626          * Do nothing (and _don't_ bypass).
 1627          * Wait to vrele lowervp until reclaim,
 1628          * so that until then our union_node is in the
 1629          * cache and reusable.
 1630          *
 1631          */
 1632 
 1633         if (un->un_dircache != NULL)
 1634                 union_dircache_free(un);
 1635 
 1636 #if 0
 1637         if ((un->un_flags & UN_ULOCK) && un->un_uppervp) {
 1638                 un->un_flags &= ~UN_ULOCK;
 1639                 VOP_UNLOCK(un->un_uppervp, 0, td);
 1640         }
 1641 #endif
 1642 
 1643         if ((un->un_flags & UN_CACHED) == 0)
 1644                 vgone(vp);
 1645 
 1646         return (0);
 1647 }
 1648 
 1649 static int
 1650 union_reclaim(ap)
 1651         struct vop_reclaim_args /* {
 1652                 struct vnode *a_vp;
 1653         } */ *ap;
 1654 {
 1655         union_freevp(ap->a_vp);
 1656 
 1657         return (0);
 1658 }
 1659 
 1660 static int
 1661 union_print(ap)
 1662         struct vop_print_args /* {
 1663                 struct vnode *a_vp;
 1664         } */ *ap;
 1665 {
 1666         struct vnode *vp = ap->a_vp;
 1667 
 1668         printf("\tvp=%p, uppervp=%p, lowervp=%p\n",
 1669                vp, UPPERVP(vp), LOWERVP(vp));
 1670         if (UPPERVP(vp) != NULLVP)
 1671                 vprint("union: upper", UPPERVP(vp));
 1672         if (LOWERVP(vp) != NULLVP)
 1673                 vprint("union: lower", LOWERVP(vp));
 1674 
 1675         return (0);
 1676 }
 1677 
 1678 static int
 1679 union_pathconf(ap)
 1680         struct vop_pathconf_args /* {
 1681                 struct vnode *a_vp;
 1682                 int a_name;
 1683                 int *a_retval;
 1684         } */ *ap;
 1685 {
 1686         int error;
 1687         struct thread *td = curthread;          /* XXX */
 1688         struct union_node *un = VTOUNION(ap->a_vp);
 1689         struct vnode *vp;
 1690 
 1691         vp = union_lock_other(un, td);
 1692         KASSERT(vp != NULL, ("union_pathconf: backing vnode missing!"));
 1693 
 1694         ap->a_vp = vp;
 1695         error = VOP_PATHCONF_AP(ap);
 1696         union_unlock_other(vp, td);
 1697 
 1698         return (error);
 1699 }
 1700 
 1701 static int
 1702 union_advlock(ap)
 1703         struct vop_advlock_args /* {
 1704                 struct vnode *a_vp;
 1705                 caddr_t  a_id;
 1706                 int  a_op;
 1707                 struct flock *a_fl;
 1708                 int  a_flags;
 1709         } */ *ap;
 1710 {
 1711         register struct vnode *ovp = OTHERVP(ap->a_vp);
 1712 
 1713         ap->a_vp = ovp;
 1714         return (VOP_ADVLOCK_AP(ap));
 1715 }
 1716 
 1717 
 1718 /*
 1719  * XXX - vop_strategy must be hand coded because it has no
 1720  * YYY - and it is not coherent with anything
 1721  *
 1722  * vnode in its arguments.
 1723  * This goes away with a merged VM/buffer cache.
 1724  */
 1725 static int
 1726 union_strategy(ap)
 1727         struct vop_strategy_args /* {
 1728                 struct vnode *a_vp;
 1729                 struct buf *a_bp;
 1730         } */ *ap;
 1731 {
 1732         struct buf *bp = ap->a_bp;
 1733         struct vnode *othervp = OTHERVP(ap->a_vp);
 1734 
 1735 #ifdef DIAGNOSTIC
 1736         if (othervp == NULLVP)
 1737                 panic("union_strategy: nil vp");
 1738         if ((bp->b_iocmd == BIO_WRITE) &&
 1739             (othervp == LOWERVP(ap->a_vp)))
 1740                 panic("union_strategy: writing to lowervp");
 1741 #endif
 1742         return (VOP_STRATEGY(othervp, bp));
 1743 }
 1744 
 1745 static int
 1746 union_getacl(ap)
 1747         struct vop_getacl_args /* {
 1748                 struct vnode *a_vp;
 1749                 acl_type_t a_type;
 1750                 struct acl *a_aclp;
 1751                 struct ucred *a_cred;
 1752                 struct thread *a_td;
 1753         } */ *ap;
 1754 {
 1755         int error;
 1756         struct union_node *un = VTOUNION(ap->a_vp);
 1757         struct vnode *vp;
 1758 
 1759         vp = union_lock_other(un, ap->a_td);
 1760         ap->a_vp = vp;
 1761         error = VOP_GETACL_AP(ap);
 1762         union_unlock_other(vp, ap->a_td);
 1763 
 1764         return (error);
 1765 }
 1766 
 1767 static int
 1768 union_setacl(ap)
 1769         struct vop_setacl_args /* {
 1770                 struct vnode *a_vp;
 1771                 acl_type_t a_type;
 1772                 struct acl *a_aclp;
 1773                 struct ucred *a_cred;
 1774                 struct thread *a_td;
 1775         } */ *ap;
 1776 {
 1777         int error;
 1778         struct union_node *un = VTOUNION(ap->a_vp);
 1779         struct vnode *vp;
 1780 
 1781         vp = union_lock_other(un, ap->a_td);
 1782         ap->a_vp = vp;
 1783         error = VOP_SETACL_AP(ap);
 1784         union_unlock_other(vp, ap->a_td);
 1785 
 1786         return (error);
 1787 }
 1788 
 1789 static int
 1790 union_aclcheck(ap)
 1791         struct vop_aclcheck_args /* {
 1792                 struct vnode *a_vp;
 1793                 acl_type_t a_type;
 1794                 struct acl *a_aclp;
 1795                 struct ucred *a_cred;
 1796                 struct thread *a_td;
 1797         } */ *ap;
 1798 {
 1799         struct vnode *ovp = OTHERVP(ap->a_vp);
 1800 
 1801         ap->a_vp = ovp;
 1802         return (VOP_ACLCHECK_AP(ap));
 1803 }
 1804 
 1805 static int
 1806 union_closeextattr(ap)
 1807         struct vop_closeextattr_args /* {
 1808                 struct vnode *a_vp;
 1809                 int a_commit;
 1810                 struct ucred *a_cred;
 1811                 struct thread *a_td;
 1812         } */ *ap;
 1813 {
 1814         int error;
 1815         struct union_node *un = VTOUNION(ap->a_vp);
 1816         struct vnode *vp;
 1817 
 1818         vp = union_lock_other(un, ap->a_td);
 1819         ap->a_vp = vp;
 1820         error = VOP_CLOSEEXTATTR_AP(ap);
 1821         union_unlock_other(vp, ap->a_td);
 1822 
 1823         return (error);
 1824 }
 1825 
 1826 static int
 1827 union_getextattr(ap)
 1828         struct vop_getextattr_args /* {
 1829                 struct vnode *a_vp;
 1830                 int a_attrnamespace;
 1831                 const char *a_name;
 1832                 struct uio *a_uio;
 1833                 size_t *a_size;
 1834                 struct ucred *a_cred;
 1835                 struct thread *a_td;
 1836         } */ *ap;
 1837 {
 1838         int error;
 1839         struct union_node *un = VTOUNION(ap->a_vp);
 1840         struct vnode *vp;
 1841 
 1842         vp = union_lock_other(un, ap->a_td);
 1843         ap->a_vp = vp;
 1844         error = VOP_GETEXTATTR_AP(ap);
 1845         union_unlock_other(vp, ap->a_td);
 1846 
 1847         return (error);
 1848 }
 1849 
 1850 static int
 1851 union_listextattr(ap)
 1852         struct vop_listextattr_args /* {
 1853                 struct vnode *a_vp;
 1854                 int a_attrnamespace;
 1855                 struct uio *a_uio;
 1856                 size_t *a_size;
 1857                 struct ucred *a_cred;
 1858                 struct thread *a_td;
 1859         } */ *ap;
 1860 {
 1861         int error;
 1862         struct union_node *un = VTOUNION(ap->a_vp);
 1863         struct vnode *vp;
 1864 
 1865         vp = union_lock_other(un, ap->a_td);
 1866         ap->a_vp = vp;
 1867         error = VOP_LISTEXTATTR_AP(ap);
 1868         union_unlock_other(vp, ap->a_td);
 1869 
 1870         return (error);
 1871 }
 1872 
 1873 static int
 1874 union_openextattr(ap)
 1875         struct vop_openextattr_args /* {
 1876                 struct vnode *a_vp;
 1877                 struct ucred *a_cred;
 1878                 struct thread *a_td;
 1879         } */ *ap;
 1880 {
 1881         int error;
 1882         struct union_node *un = VTOUNION(ap->a_vp);
 1883         struct vnode *vp;
 1884 
 1885         vp = union_lock_other(un, ap->a_td);
 1886         ap->a_vp = vp;
 1887         error = VOP_OPENEXTATTR_AP(ap);
 1888         union_unlock_other(vp, ap->a_td);
 1889 
 1890         return (error);
 1891 }
 1892 
 1893 static int
 1894 union_deleteextattr(ap)
 1895         struct vop_deleteextattr_args /* {
 1896                 struct vnode *a_vp;
 1897                 int a_attrnamespace;
 1898                 const char *a_name;
 1899                 struct ucred *a_cred;
 1900                 struct thread *a_td;
 1901         } */ *ap;
 1902 {
 1903         int error;
 1904         struct union_node *un = VTOUNION(ap->a_vp);
 1905         struct vnode *vp;
 1906 
 1907         vp = union_lock_other(un, ap->a_td);
 1908         ap->a_vp = vp;
 1909         error = VOP_DELETEEXTATTR_AP(ap);
 1910         union_unlock_other(vp, ap->a_td);
 1911 
 1912         return (error);
 1913 }
 1914 
 1915 static int
 1916 union_setextattr(ap)
 1917         struct vop_setextattr_args /* {
 1918                 struct vnode *a_vp;
 1919                 int a_attrnamespace;
 1920                 const char *a_name;
 1921                 struct uio *a_uio;
 1922                 struct ucred *a_cred;
 1923                 struct thread *a_td;
 1924         } */ *ap;
 1925 {
 1926         int error;
 1927         struct union_node *un = VTOUNION(ap->a_vp);
 1928         struct vnode *vp;
 1929 
 1930         vp = union_lock_other(un, ap->a_td);
 1931         ap->a_vp = vp;
 1932         error = VOP_SETEXTATTR_AP(ap);
 1933         union_unlock_other(vp, ap->a_td);
 1934 
 1935         return (error);
 1936 }
 1937 
 1938 static int
 1939 union_setlabel(ap)
 1940         struct vop_setlabel_args /* {
 1941                 struct vnode *a_vp;
 1942                 struct label *a_label;
 1943                 struct ucred *a_cred;
 1944                 struct thread *a_td;
 1945         } */ *ap;
 1946 {
 1947         int error;
 1948         struct union_node *un = VTOUNION(ap->a_vp);
 1949         struct vnode *vp;
 1950 
 1951         vp = union_lock_other(un, ap->a_td);
 1952         ap->a_vp = vp;
 1953         error = VOP_SETLABEL_AP(ap);
 1954         union_unlock_other(vp, ap->a_td);
 1955 
 1956         return (error);
 1957 }
 1958 
 1959 /*
 1960  * Global vfs data structures
 1961  */
 1962 struct vop_vector union_vnodeops = {
 1963         .vop_default =          &default_vnodeops,
 1964 
 1965         .vop_access =           union_access,
 1966         .vop_aclcheck =         union_aclcheck,
 1967         .vop_advlock =          union_advlock,
 1968         .vop_bmap =             VOP_EOPNOTSUPP,
 1969         .vop_close =            union_close,
 1970         .vop_closeextattr =     union_closeextattr,
 1971         .vop_create =           union_create,
 1972         .vop_deleteextattr =    union_deleteextattr,
 1973         .vop_fsync =            union_fsync,
 1974         .vop_getacl =           union_getacl,
 1975         .vop_getattr =          union_getattr,
 1976         .vop_getextattr =       union_getextattr,
 1977         .vop_getwritemount =    union_getwritemount,
 1978         .vop_inactive =         union_inactive,
 1979         .vop_ioctl =            union_ioctl,
 1980         .vop_lease =            union_lease,
 1981         .vop_link =             union_link,
 1982         .vop_listextattr =      union_listextattr,
 1983         .vop_lookup =           union_lookup,
 1984         .vop_mkdir =            union_mkdir,
 1985         .vop_mknod =            union_mknod,
 1986         .vop_open =             union_open,
 1987         .vop_openextattr =      union_openextattr,
 1988         .vop_pathconf =         union_pathconf,
 1989         .vop_poll =             union_poll,
 1990         .vop_print =            union_print,
 1991         .vop_read =             union_read,
 1992         .vop_readdir =          union_readdir,
 1993         .vop_readlink =         union_readlink,
 1994         .vop_reclaim =          union_reclaim,
 1995         .vop_remove =           union_remove,
 1996         .vop_rename =           union_rename,
 1997         .vop_rmdir =            union_rmdir,
 1998         .vop_setacl =           union_setacl,
 1999         .vop_setattr =          union_setattr,
 2000         .vop_setextattr =       union_setextattr,
 2001         .vop_setlabel =         union_setlabel,
 2002         .vop_strategy =         union_strategy,
 2003         .vop_symlink =          union_symlink,
 2004         .vop_whiteout =         union_whiteout,
 2005         .vop_write =            union_write,
 2006 };

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